Korean J Radiol.  2014 Aug;15(4):448-455. 10.3348/kjr.2014.15.4.448.

Serial Micro-CT Assessment of the Therapeutic Effects of Rosiglitazone in a Bleomycin-Induced Lung Fibrosis Mouse Model

• Choi EJ
• Jin GY
• Bok SM
• Han YM
• Lee YS
• Jung MJ
• Kwon KS

• KMID: 1731048
• DOI: http://doi.org/10.3348/kjr.2014.15.4.448

Abstract

OBJECTIVE
The aim of this study was to assess the therapeutic effects of rosiglitazone with serial micro-CT findings before and after rosiglitazone administration in a lung fibrosis mouse model induced with bleomycin.
MATERIALS AND METHODS
We instilled the bleomycin solution directly into the trachea in twenty mice (female, C57BL/6 mice). After the instillation with bleomycin, mice were closely observed for 3 weeks and then all mice were scanned using micro-CT without sacrifice. At 3 weeks, the mice were treated with rosiglitazone on days 21 to 27 if they had abnormal CT findings (n = 9, 45%). For the mice treated with rosiglitazone, we performed micro-CT with mouse sacrifice 2 weeks after the rosiglitazone treatment completion. We assessed the abnormal CT findings (ground glass attenuation, consolidation, bronchiectasis, reticular opacity, and honeycombing) using a five-point scale at 3 and 6 weeks using Wilcoxon-signed ranked test. The micro-CT findings were correlated with the histopathologic results.
RESULTS
One out of nine (11.1%) mice improved completely. In terms of consolidation, all mice (100%) showed marked decrease from 3.1 +/- 1.4 at 3 weeks to 0.9 +/- 0.9 at 6 weeks (p = 0.006). At 6 weeks, mild bronchiectasis (n = 6, 66.7%), mild reticular opacity (n = 7, 77.8%) and mild honeycomb patterns (n = 3, 33.3%) appeared.
CONCLUSION
A serial micro-CT enables the evaluation of drug effects in a lung fibrosis mouse model.

Keyword

Microcomputed tomography; Bleomycin; Fibrosis; Rosiglitazone; Lung

MeSH Terms

Animals
Bleomycin
Disease Models, Animal
Female
Mice
Mice, Inbred C57BL
Observer Variation
Pulmonary Fibrosis/chemically induced/*drug therapy/*radiography
Thiazolidinediones/*therapeutic use
*X-Ray Microtomography
Bleomycin
Thiazolidinediones

Figure

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  Fig. 1 Schematic diagram of experimental protocol. Control mice were instilled with saline into both lungs through tracheal cannula. In experimental group, bleomycin solution (60 µL as single dose) was instilled directly into trachea. Micro-CT was performed 3 weeks after instillation of bleomycin. When mice showed abnormal findings on micro-CT, rosiglitazone (5 mg/kg body weight/day) dissolved in distilled water was delivered seven times by oral gavage with 24-hour interval from days 21 to 27. Micro-CT was performed in mice treated with rosiglitazone to define effects of agent on lung 2 weeks after completion of rosiglitazone treatment.

• 

  Fig. 2 Mouse lung imaging performed using micro-CT scanner. Micro-CT image is provided with ruler which is generated by scanner system.

• 

  Fig. 3 Example of scoring of severity of consolidation on micro-CT. Severity of findings on imaging before and after rosiglitazone instillation in bleomycin-induced fibrosis mice model was semiquantitatively assessed on five-point scale. Consolidation was scored on 0 to 5 scale (absent = 0, less than 5% = 1, 5-25% = 2, 25-50% = 3, 50-75% = 4, more than 75% = 5) depending on area involved.

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  Fig. 4 Normal micro-CT finding of control mice. Micro-CTs of control mice show all normal findings at 3 and 6 weeks after intratracheal saline instillation.

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  Fig. 5 Case of improvement of lung fibrosis after administration of rosiglitazone shown on micro-CT. A. There is bilateral consolidation on micro-CT 3 weeks after bleomycin instillation. B. This is micro-CT image 6 weeks after bleomycin instillation. This mouse showed reduced bilateral consolidation, ground glass attenuation and bronchiectasis in same areas after administration of rosiglitazone. C. Interstitium is thickened by inflammatory cell infiltration on microscopy (hematoxylin and eosin stain, × 25).

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  Fig. 6 Case of complete improvement of lung fibrosis after administration of rosiglitazone shown on micro-CT. A. There is diffuse peribronchial wall thickening, consolidation and ground glass attenuation on micro-CT 3 weeks after bleomycin instillation. B. This is micro-CT image 6 weeks after bleomycin instillation. Consolidation improved completely in same area 3 weeks after rosiglitazone treatment. C. There is minimal or no inflammatory cell infiltration in interstitium as seen on microscopy (hematoxylin and eosin stain, × 25).

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